Digital Mammography offers important potential advantages for early detection of breast Cancer: 1) improved image quality; 2) digital image processing; 3) computer-aided diagnosis; and 4) teleradiology for facilitated radiologic consultation 1. There are two significant limitations that digital systems must address in order to be successful: limited spatial resolution caused by focal spot blurring and by the detector itself, and detection of scattered radiation. Glass capillary x-ray optics have properties that make them ideally suited to address these two problems. The aims of this continuation proposal are to investigate the use of x-ray capillary optics for mammography and chest radiography. During the current grant the optics have performed very much as predicted for mammographic applications. However, large area arrays of polycapillaries are not yet available. Therefore this proposal will focus on the use of multi-element optics; ie. several smaller optics coupled together to form one large optic. Measurements of capillary optic performance at higher energies suitable for chest radiography is significantly more difficult than at the lower energies. We propose to continue these measurements at a modest level of effort. The following investigations will be performed. The basic properties of multi-element optics will be measured; including consistency of focal length, transmission, linearity, and size. Scatter rejection, contrast improvement, resolution, and MTF will be measured in static and scanning configurations. A prototype multi-element (3 to 5 optics) optic will be investigated: resolution/MTF, contrast improvement, scatter reduction, and image artifacts. A close-packed multi-element optic will be designed and fabricated based on the results with the prototype optic. Observer performance will be studied using phantoms to determine radiologists' ability to detect and characterize calcifications and masses. The properties of capillary optics will be investigated at the higher energies suitable for chest radiography.